This paper describes current and proposed protocols for mobility management for public land mobile network (PLMN)-based networks, mobile Internet protocol (IP) wireless asynchronous transfer mode (ATM) and satellite networks. The integration of these networks will be discussed in the context of the next evolutionary step of wireless communication networks. First, a review is provided of location management algorithms for personal communication systems (PCS) implemented over a PLMN network. The latest protocol changes for location registration and handoff are investigated for mobile IP followed by a discussion of proposed protocols for wireless ATM and satellite networks. Finally, an outline of open problems to be addressed by the next generation of wireless network service is discussed.

http://www.cs.tcd.ie/~htewari/papers/ieee99.pdf

Mobility management in next-generation wireless systems

A communication system providing telephony communication across combined circuit switched and packet switched networks, such as a telephone network and the Internet, which are connectable to terminals, such as telephones and computers, for selective communication therebetween. The communication system includes an authorization and account control object in the packet switched network, multiple gateways between the circuit switched and packet switched networks providing controlled connectivity between those networks, and an information retrieval object in the packet switched network, wherein the authorization and account control object maintains a substantially real time record of user accounts and usage, and the information and retrieval object provides substantially real time retrieval of selected information from the authorization and account control object. The retrieval object provides on demand to terminals which provide authentication for access to an identified account information regarding that account. The information regarding the account is substantially real time information including information with respect to communications in progress, which are chargeable to the account which has been authenticated. The authorization and account control object is preferably a unitary logical object having distributed instances thereof handling multitudinous accounts of widely separated terminals. The retrieval object provides isolation of the authorization and account control object permitting simultaneous multitasking by the authorization and account control object and the retrieval object respectively.

Network session management

Location tracking operations in a personal communications services (PCSs) network are expensive. Several strategies have been proposed to reduce the location update cost. This paper studies a special case of a location tracking algorithm called the alternative location algorithm. This special case is referred to as the two location algorithm (TLA). An analytical model is proposed to compare the performance of the TLA and the IS-41 protocol. Our study indicates that the performance of the TLA is significantly affected by the user moving patterns and the call traffic. If the user mobility is higher than the call frequency or the user tends to move back to the previously visited registration areas, then the TLA may significantly outperform IS-41. We also observe that the variance of the portable residence times in registration areas has an impact on the performance of the TLA (i.e., better performance is expected for larger variance).

https://ir.nctu.edu.tw:443/bitstream/11536/732/1/A1997WM61100003.pdf

Reducing location update cost in a PCS network

W ith the increasing use of small portable computers, wireless networks, and satellites, a trend to support computing on the move has emerged—this trend is known as mobile computing or nomadic computing [3]. Also referred to as anytime/anywhere computing, mobile computing has several interesting and important applications for business (such as instant claim processing and e-commerce), telecommunications and personal communications, national defense (tracking troop movements), emergency and disaster management, real-time control systems, remote operation of appliances, and in accessing the Internet. Since a user may not maintain a fixed position in such environments, the mobile and wireless networking support allowing mobile users to communicate with other users (fixed or mobile) becomes crucial. A possible scenario may involve several different networks that can support or can be modified to support mobile users. When dealing with different wireless networks, a universal mobile device should be able to select the network (LAN, the Internet, PCS, or satellite) that best meets user requirements. Wireless and mobile networks have provided the flexibility required for an increasingly mobile workforce. As shown in Figure 1(a), the worldwide number of cellular, GSM, and PCS subscribers increased from 140 million in 1996 to over 300 million in 1999 and is expected to grow to 650 million by 2001 (see www.gsmdata.com). In the U.S., capital investment increased from $6.3 billion in 1990 to $66.8 billion in 1999 and service revenues were up from $4.5 billion to $38.7 billion in 1999 (see www.wow-com.com) as shown in Figure 1(b). During the same period, the average local monthly bill diminished from $80 to $39 as shown in Figure 1(c), indicating the technological maturity and the tremendous competition among service providers. Many general remarks can be made about wireless systems. First, the channel capacity typically available in wireless systems is much lower than what is Upkar Varshney and Ron Vetter

Emerging mobile and wireless networks

Channel holding time is of primary importance in teletraffic analysis of PCS networks. This quantity depends on user's mobility which can be characterized by the cell residence time. We show that when the cell residence time is not exponentially distributed, the channel holding time is not exponentially distributed either, a fact also confirmed by available field data. In order to capture the essence of PCS network behaviour, including the characterization of channel holding time, a correct mobility model is therefore necessary. The new model must be good enough to fit field data, while at the same time resulting in a tractable queueing system. We propose a new mobility model, called the hyper-Erlang distribution model, which is consistent with these requirements. Under the new realistic operational assumption of this model, in which the cell residence time is generally distributed, we derive analytical results for the channel holding time distribution, which are readily applicable to the hyper-Erlang distribution models. Using the derived analytical results we demonstrate how the distribution of the cell residence time affects the channel holding time distribution. The results presented in this paper can provide guidelines for field data processing in PCS network design and performance evaluation.

Teletraffic analysis and mobility modeling of PCS networks

The Personal Access Communications System (PACS) is an American National Standards Institute common air interface standard developed for the 1.9 GHz PCS band in the United States. PACS uses frequency division duplexing technology and is optimized to support low-mobility pedestrian outdoor usage and wireless local loop applications in a medium-range environment. PACS-Unlicensed B (PACS-UB) is a version of PACS using time division duplexing. PACS-UB has been optimized for private, indoor wireless PBX applications and cordless telephony. Both modes of operation are supported using the same portable hardware and the same signaling protocol.

https://ir.nctu.edu.tw:443/bitstream/11536/1257/1/A1996UT89900002.pdf

PACS: Personal Access Communications System-a tutorial

Wireless local loop (WLL) provides two-way calling services to the stationary or "fixed" users, which is intended to replace its wireline counterpart. Today, there are almost 100 WLL systems (either trials or commercial systems). This article describes the WLL architecture, the WLL technologies, WLL service descriptions, and some examples of WLL products.

https://ir.nctu.edu.tw:443/bitstream/11536/32568/1/000074420700009.pdf

Wireless local loop: architecture, technologies and services

Registration/deregistration is required in a PCS network when a portable moves between registration areas. Several schemes were proposed to deregister a portable after it moves out of a registration area (RA). A simple scheme called implicit deregistration totally eliminates network traffic due to deregistration. However, this scheme may delete valid registration records. Thus, the size of a registration database must be sufficiently large to ensure low probability that a valid registration record is deleted. This paper describes an analytic model to determine the size k of the registration database for an RA in the implicit deregistration scheme. If the expected number of portables in an RA is N, then our study indicates that good performance can be achieved if k/spl sime/5N. >

Implicit deregistration in a PCS network

The FCC has allocated the spectrum between 1850-1910 and 1930-1990 MHz for licensed personal communications services (PCS) and the band between 1920-1930 MHz for unlicensed PCS (UPCS). This paper describes a polling deregistration protocol for a wireless access communications network which would support interoperability between licensed personal communications services (PCS) and unlicensed-PCS (UPCS). We show how the protocol can be efficiently implemented in the personal access communications system (PACS) for licensed PCS and in the PACS-Unlicensed Version B (PACS-UB). An analytical model is proposed to analyze the performance of the polling protocol. A cost function is derived, which can be used to estimate the optimal polling frequency.

/pdf/polling-deregistration-for-unlicensed-pcs-3pmz68r430.pdf

Polling deregistration for unlicensed PCS

The emergence of multitier wireless access is being driven by the different compromises in technology required to provide wireless service in different environments. Three major tiers of wireless access are likely to emerge to providepersonal communications services (PCS): high-tier, low-tier, and unlicensed. Because of the service costs of the three tiers, the unlicensed system is given the highest priority to deliver the calls, and the high-tier system has the lowest priority to deliver the calls. To maintain this delivery priority, two multitier mobility management strategies have been proposed: the single registration strategy (SR) and the modified multiregistration strategy (MR). This paper proposes a new strategy called the lazy deregistration strategy (LDR) and compares the performance of the three strategies. We show that in most cases, LDR outperforms both SR and MR. The registration cost of SR is always no less than the cost of MR. The advantage of MR over SR is more significant if (i) when the user moves into the low-tier system, it is more likely that the currently visited low-tier VLR (visitor location register) is the same as the previously visited VLR, and (ii) the mobile station (MS) is more likely to move between the low-tier system and the high-tier system. The call delivery cost of MR is always no less than the cost of SR. The advantage of SR over MR is more significant if (i) the call arrival rate is large, (ii) the cost of delivering a call to the low-tier system is large, and (iii) the MS is likely to stay in the high-tier system.

A.R. Noerpel

Papers

PACS: Personal Access Communications System-a tutorial

Wireless local loop: architecture, technologies and services

Implicit deregistration in a PCS network

Polling deregistration for unlicensed PCS

Performance modeling of multitier PCS system